Graphene for Supercontinuum Generation

In our most recent paper, my student and I looked at exploiting non-linearity of Graphene in a plasmonic structure for Supercontinuum Generation (SCG).

This work has been exciting to us for many reasons:

  • working on 2D materials. Graphene is a quick start and we are exploring other 2D materials and novel materials as well
  • exploiting plasmonic effects to go beyond sensing applications
  • we found Graphene behaving as a metal without negative permittvity and saw formation of Surface Plasmon Polaritons (SPP) at 300 and 371K. To us this is really exciting and could mean some new Physics lies in wait for exploration.

We generated a multi-octave broadband SC spectrum ranging from 1.5–25 micron at a low input peak power of 1 W.

Typically we expect that at a metal-dielectric interface, SPPs are formed when

k2/k1  = − ε2/ε1 ,

where ε2 and ε1 are the
permittivity of the metal and dielectric respectively. In our case, the permittivity of Graphene is not negative,  however we still observe the formation of SPPs. The values we obtained are summarised below:

graphene permittivity

Calculated conductivity and permittivity of single layer Graphene at 1550 nm for 450 meV and  500 meV – 300 K and 371 K

This performance SC spectrum ranging from 1.5–25 micron was possible due to the high Kerr non-linearity of Graphene and also the tailored waveguide dispersion we obtained.


Look out for more on this…




Paid Access journals: some thoughts

In a recent post (Open Access: needs more work!) I wrote on how Article Publishing Charges (APC) can hinder equality in the gold route of OA publishing.

Today, I want to discuss the paid access traditional journals and publishers.

The boycott of Elsevier highlighted like nothing else the downsides of the business model employed by many professional publishers. I list only a few below:

–          Using Government/taxpayer funded research to generate profit without contributing to research funding

–          No sharing of revenues with authors

–          Not paying the reviewers members of editorial work for their labour

–          Bundling of several journals and selling journal access at very high prices

Yet I argue that these journals and publishers have an important role and place in academic publishing in the future, provided they make some key changes (given later).


Well, here are some reasons:

–          Some journals have been established for decades and are well recognized. There is benefit to authors by publishing (citation, impact, recognition, prestige) and to readers as they feel the quality of work is good.

–          It takes a long time and a lot of resource to establish a new journal, and so should we neglect what has been built over the years, if it can be adapted?

–          OA (gold route) shifts the cost burden entirely onto authors via APCs- pricing out some authors, see Open Access: needs more work! while traditional subscription-based journals put the entire cost burden onto readers, allowing authors (even those that are resource-strapped) to publish in good journals. (Caveat: these may increasingly have lower citation rates and impact factors than the top OA journals)

–          Membership of editorial boards of such journals is a factor in success with promotions, jobs and grant applications; it is a marker of seniority in the profession.

So clearly the gold OA (authors pay all) and traditional journal publishing model (reader pay all) are at opposite ends of the spectrum. Each has its benefits and problems. I think we need journals from both business models to meet the diverse needs of a global research community.

However, the ‘reader pay all’ or traditional model needs changes to survive and thrive in the advent of OA.

What changes would I suggest?

–          Charge for individual journals rather than bundles, with a sensible pricing model

–          Pay editors and reviewers fairly for their work

–          Share revenue with authors: for example, after each year work out the profit a journal has made and share a percentage of the profit with authors (profit/number of articles)

In addition, by revenue sharing these publishers will incentivize authors and the larger academic community to continue reading, publishing and reviewing articles for their journals.

While this will obviously reduce the profit to publishers and their shareholders, it will perhaps make them sustainable. Sustainability and survival, in my view, make a sufficiently strong business case for change.

All of the above will no doubt be hideously complicated and perhaps not implementable in form suggested. I hope though, that it leads people to propose improvements that are indeed feasible.

Open Access: needs more work!

Open Access (OA) journals have made a massive impact in the world of academic publishing. A handful of such journals has grown into a massive access

Much has been written about OA, the gold(authors pay the publication charges for their articles which are free to download) and green (authors can place a copy of their articles in pre-print or post-print format in online repositories operated by their universities or databases such as Arxiv, see more on the Romeo project) routes (see also Open access funding models), its power and the boycott of established publishers such as Elsevier, the Finch report  and much more, see (OASIS, We neet to talk about kevin , er, open access etc.

Clearly OA is here to stay and has a lot of power- on average open-access articles are cited 176% more often than print/paid-subscription articles (see for example, bibliography on studies on impact of open access, Swan 2010). Is it then the path to information for all, the true access to knowledge for all?

At this point it is also worth mentioning that there are some very big discipline specific factors that affect OA journals. There are reports that compare Humanities and Social Sciences and Science (HSS) with Science, Technology and Medicine (STM) journals see for example this link.

I believe that open access to research is part of the story, not all of it.

The debate on OA has focused a lot (especially with regards to STM journals) on the benefits to readers. Implicit in this is the assumption that all authors have equal access to publication in OA journals[1].

I want to discuss this assumption.

As the number of open access journals, the frequency of issues and number of articles increase, the net effect is a massive information deluge that a reader cannot cope with. The result is that readers apply selection criteria to filter out and read some journals more regularly than others. Quality of articles, impact factors and citation rates influence the selection among other factors. Thus, not all quality work and journals get the same readership.

The knock-on effect is that authors increasingly want to publish in the journals that give their work the most impact. This means journals with higher citation rates and large impact factors, large readership, and strategic readers. The competition is for eyeballs and for article space in some of these highly prized open access journals.

This is where the issue of publication charges becomes crucial.

I take the example of my research area of Optics, in which the OA journals that figure in the top 20 (ranked by 5 year Impact Factor (IF)) are Optics Express (ranked 4 with 5 year IF=3.666), IEEE Photonics Journal (ranked 13 with IF=2.320), see Journal Citation reports. All the OA journals have publication charges. The minimum charges for Optics Express and IEEE Photonics Journal are over $1000 (see links to Optics Express publication fees, IEEE Photonics Journal charges).

Publication charges can price out researchers from

1. Individuals/small groups/universities with relatively modest funding

2. Researchers from poorer countries, currency conversion rates further exacerbate the pain

Though authors can still publish in the traditional journals that do not charge a publication fee and then make their work freely available through online repositories (the green route to OA), this has problems:

1. Difference in impact factors will still affect these authors when applying for grants, jobs, promotions etc., i.e. anything competitive where journal prestige and citations are important.

2. Its not completely certain their work will get the same attention (?)  (if published in a non OA journal).

Consider for example: Optics Express has a higher number of total cites (54094, ranked 2nd by number of cites for all Optics journals and 5th by 5year IF) than its much older and also very prestigious sister journal Optics Letters (ranked 3rd by total number of cited-45759, and 7th by 5 year IF), even though Optics Express is only in its 20th year, while Optics Letters is in its 37th year of publication. Source: Journal Citation reports from Web of Science, figures taken on 5th October 2012.

3. Not all institutions worldwide have online repositories, or all disciplines suitable online archives

Thus the gold route to OA where the burden of publication charges is borne solely by the authors can also lead to inequality: some can afford to publish in the best OA journals, while some cant!

Can we afford this sort of inequality in research? Do we want it?

If we cant read the interesting, novel, unique work done by talented people from diverse backgrounds the entire research community would be poorer. We would all suffer in that if the quality of what we read is not the best possible, our own output cannot be the best possible.

To me this suggests that OA needs more work for it to truly serve the research community. We need to find a way to distribute the publishing costs so that deserving authors are not priced out of publishing and readers are not (as a result priced out) of reading such work.

[1] On his website librarian Micah VanderGrift  quotes from a study by Suber and Sutton that 83% of OA journals by learned society publishers do not charge publication fees. This figure is an overview of OA journals across disciplines, hence the scenario could be very different for individual disciplines/areas.